In the past, when a patient had lost most of his or her teeth, and where the remaining teeth are mobile, it was common practice to remove the remaining few teeth and to fit the patient with a complete mucosa-supported denture. This however had, and has, serious disadvantages for the patient.
Thus, the removal of all natural teeth provokes resorption of the roots which in turn causes a poor aesthetic effect, reduces the stability and retention of dentures and may cause psychological problems for the patient.
On the other hand, if most natural teeth have been lost, the forces acting on the remaining teeth, for example during mastication, are enormous, and eventually such teeth lose their alveolar bone support and become mobile and painful.